ms.lane

Dremel is probably a bit overboard, a utility knife will do it. But you’re right, there can be required modification (or just using a 1x to 16x riser for ~$2 from AliExpress)

RasPi isn’t actually very efficient for what it is.

As otherwise mentioned a 16x/8x/4x card can be used in a 1x slot.

Any 1x physical GPU will be extremely overpriced for what it is as they’re incredibly niche products.